Note: Descriptions are shown in the official language in which they were submitted.
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COATING MATERIAL, METHOD FOR THE PRODUCTION AND
USE THEREOF, FOR PRODUCING ADHESIVE,
CORROSION-INHIBITING COATINGS
Field of the Invention
The present invention relates to a new coating material curable with actinic
radiation. The
present invention also relates to a new process for preparing a coating
material curable
with actinic radiation. The present invention further relates to the use of
the new coating
material or of the coating material prepared by means of the new process to
produce
thermally adhering, corrosion-inhibiting coatings, particularly coil coatings,
especially
primer coats.
Prior Art
In order to produce thermally adhering, corrosion-inhibiting coatings on metal
strips or
coils, particularly those made from the conventional utility methods, such as
zinc,
aluminum or bright, galvanized, electrolytically zincked, and phosphated
steel, by means
of the coil coating process (Rompp Lexikon Lacke und Druckfarben, Georg Thieme
Verlag, Stuttgart, New York, 1998, page 617, "Roll coating", and page 55,
"Coil coating") it
is necessary to pretreat the surface of the metal coils. As part of the coil
coating process,
however, this represents an additional step, which it would be desirable to
avoid on
economic and technical grounds.
Primer coats serve, as is known, to promote adhesion between the metal surface
and the
coatings lying above it. To a certain extent they may also contribute to
corrosion control.
They are normally produced from pigmented, solventborne, thermally curable
coating
materials. However, this necessitates complex units for the suction withdrawal
and
disposal of the emitted solvents, and the coils must be heated to high
temperatures ("peak
metal temperatures", PMT) in order to cure the applied coating materials at
the speed
which is necessary for the coil coating process. It is therefore highly
desirable to have
available solvent-free coating materials, rapidly curable with actinic
radiation, for
producing primer coats.
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German patent application DE 102 56 265 Al discloses a liquid coating material
which is
curable with actinic radiation, is substantially or entirely free from organic
solvents, is in
the form of a water-in-oil dispersion, and has a pH < 5, comprising
(A) at least one constituent selected from the group consisting of low
molecular mass,
oligomeric, and polymeric organic compounds containing at least one group
which
can be activated with actinic radiation, and also air-drying and oxidatively
drying
alkyd resins,
(B) at least one acidic ester of polyphosphoric acid and of at least one
compound (b1)
containing at least one hydroxyl group and at least one group which can be
activated with actinic radiation,
(C) at least one acidic ester of monophosphoric acid and of at least one
compound
(c1) containing at least one hydroxyl group and at least one group which can
be
activated with actinic radiation, and
(D) at least one acidic, corrosion-inhibiting pigment based on polyphosphoric
acid.
The coating material may further comprise at least one additive (E) which may
be selected
preferably from the group consisting of polyphosphoric acid, driers, non-(D),
organic and
inorganic, colored and achromatic, optical effect, electrically conductive,
magnetically
shielding, and fluorescent pigments, transparent and opaque, organic and
inorganic fillers,
nanoparticies, antisettling agents, non-(A) oligomeric and polymeric binders,
UV
absorbers, light stabilizers, free-radical scavengers, photoinitiators,
devolatilizers, slip
additives, polymerization inhibitors, defoamers, non-(C) emulsifiers and
wetting agents,
adhesion promoters, leveling agents, film-forming assistants, rheology control
additives,
and flame retardants.
The known coating material is easily to prepare, of high reactivity and yet
good storage
stability, can be applied easily and without problems, particularly in the
coil coating
process, and can be cured rapidly at low curing temperatures without emitting
volatile
organic compounds. It yields coatings, particularly coil coatings, especially
primer
coatings, which, even on unpretreated metal surfaces, particularly the surface
of utility
metals, such as zinc, aluminum or bright, galvanized, electrolytically
zincked, and
phosphated steel, have high adhesion, high intercoat adhesion with respect to
the
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coatings lying above them, and an outstanding corrosion control effect,
particularly with
respect to white corrosion.
The continually growing requirements of the market, particularly those of the
manufacturers of coated coils and their customers, however, necessitate
further
development of this existing technical level in a wide variety of respects.
Where highly pigmented topcoats, topcoats with only slight gloss, or matt
topcoats are to
be produced, it is advisable for that purpose to use coating materials curable
with actinic
radiation, which can be cured rapidly preferably with electron beams (EBC)
(cf., e.g.,
A. Goldschmidt and H.-J. Streitberger, BASF-Handbuch Lackiertechnik, Vincentz
Verlag,
Hannover, 2002, pages 638 to 641). Because of the high pigment content, curing
with UV
radiation is difficult if not impossible. It has emerged, however, that the
primer coatings
produced from the known coating material, by curing with EBC and under inert
gas, do not
attain the performance level of primer coatings produced by curing with UV
radiation and
heat. In particular they do not achieve the requisite direct adhesion to
unpretreated metal
surfaces and the requisite intercoat adhesion to the highly pigmented
topcoats.
Problem Addressed
It is an object of the present invention to provide a new, pigmented coating
material which
is curable with actinic radiation, is substantially or entirely free from
organic solvents, and
no longer exhibits the disadvantages of the prior art but instead is easy to
prepare, highly
reactive and yet stable on storage, can be applied particularly easily and
without
problems, particularly as part of the coil coating process, and can be cured
very rapidly at
low curing temperatures and without emitting volatile organic compounds, and
yields
coatings, particularly coil coatings, especially primer coatings, which, even
on
unpretreated metal surfaces, particuiariy the surface of utiiity metais, such
as zinc,
aluminum or bright, galvanized, electrolytically zincked, and phosphated
steel, have
particularly high adhesion, particularly high intercoat adhesion to the
coatings lying above
them, and an outstanding corrosion control effect, particularly with respect
to white
corrosion.
The advantageous profile of performance properties of the new coatings
produced from
the new coating material ought to be obtainable even when the coating material
is cured
by means of EBC, particularly under inert conditions.
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The new coating material ought additionally to allow the production of new,
electrically
conductive, weldable coatings of outstanding corrosion control effect which
are free from
zinc or from iron phosphides. In this context the substitution of the iron
phosphides in
particular would be a particular advantage, since, on account of their high
hardness, this
class of electrically conductive pigments cause mechanical damage,
particularly through
abrasion, to the equipment during the preparation of coating materials in
question. The
new, electrically conductive, weldable coatings ought to be able to be coated
directly,
without subsequent heat curing, with electrocoat materials.
The new coatings ought, furthermore, to have particularly high flexibility and
hardness.
Solution Found
Found accordingly has been the new coating material curable with actinic
radiation,
substantially or entirely free from organic solvents and comprising
(A) at least two compounds of the general formula I:
X-O-Y(-OH)-Z-Gr (I),
in which the variables have the following definitions:
X is aromatic radical having 6 to 14 carbon atoms, heterocyclic aromatic
radical having 5 to 20 ring atoms or alkyl radical having 6 to 30 carbon
atoms,
Y is trivalent organic radical,
Z is linking functional group, and
Gr is organic radical having at least one group which can be activated with
actinic radiation;
with the proviso that at least one of the at least two compounds (A) contains
an
aromatic or heterocyclic aromatic radical X(= compound Al) and at least one of
the at least two compounds (A) contains an alkyl radical X (= compound A2);
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(B) at least one acidic, corrosion-inhibiting pigment based on polyphosphoric
acid, and
(C) at least one constituent selected from the group consisting of
nanoparticles and
electrically conductive pigments.
The new coating material is referred to below as "coating material of the
invention".
Also found has been the new process for preparing the coating material of the
invention,
which involves mixing constituents (A), (B) and (C) and also, where used, (D)
of the
coating material with one another and homogenizing the resulting mixture.
The new process is referred to below as "process of the invention".
Further inventions will emerge from the description.
In the light of the prior art it was surprising and unforeseeable for the
skilled worker that
the object on which the present invention was based could be achieved by means
of the
coating material of the invention and by means of the process of the
invention.
In particular it was surprising that the coating material of the invention no
longer had the
disadvantages of the prior art but instead was easy to prepare, highly
reactive and yet
stable on storage, could be applied particularly easily and without problems,
particularly
as part of the coil coating process, and could be cured very rapidly at
particularly low
curing temperatures and without emitting volatile organic compounds, and
yielded new
coatings, particularly coil coatings, especially primer coatings, which, even
on
unpretreated metal surfaces, particularly the surface of utility metals, such
as zinc,
aluminum or bright, galvanized, electrolytically zincked, and phosphated
steel, had
particuiariy high adhesion, par'ticuiariy high intercoat adhesion to the
coatings lying above
them, and an outstanding corrosion control effect, particularly with respect
to white
corrosion.
The advantageous profile of performance properties of the coatings of the
invention
produced from the coating material of the invention was obtained even when the
coating
material of the invention was cured by means of EBC, particularly under inert
conditions.
The coating material of the invention also allowed the production of new,
electrically
conductive, weldable coatings of outstanding corrosion control effect which
were free from
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zinc or from iron phosphides. In this context the substitution of the iron
phosphides in
particular, was a particular advantage, since, on account of their high
hardness, this class
of electrically conductive pigments caused mechanical damage, particularly by
abrasion,
to the equipment during the preparation of the coating materials in question.
The
electrically conductive, weldable coatings of the invention could be coated
directly, without
subsequent heat curing, with electrocoat materials.
Furthermore, the coatings of the invention had particularly high flexibility
and hardness.
Detailed Description of the Invention
The coating material of the invention is liquid, i.e., although it comprises
solid, non-liquid
constituents, it is nevertheless in a fluid state at room temperature under
the conventional
conditions of preparation, storage, and application, and so can be processed
by means of
the conventional application methods employed in the coil coating process.
The coating material of the invention is preferably in the form of a water-in-
oil dispersion,
in which the discontinuous aqueous phase is finely dispersed in the continuous
organic
phase. The diameter of the droplets of the aqueous phase may vary widely;
preferably it is
10 nm to 1000 pm, in particular 100 nm to 800 pm. The constituents of the
coating
material of the invention are divided between the aqueous phase and organic
phase in
accordance with their hydrophilicity or hydrophobicity (cf. Rompp Online,
2002,
"hydrophobicity", "hydrophilicity") or in the form of a separate solid phase.
The coating material of the invention, or its aqueous phase, has as a water-in-
oil
dispersion a pH of preferably < 5, more preferably < 4, and in particular from
3 to 3.5.
The coating material of the invention is substantiaiiy or entireiy free from
organic soiverits.
This means that its organic solvent content is < 5%, preferably < 3%, and more
preferably
< 1% by weight. In particular the content is below the detection limits of the
conventional
qualitative and quantitative detection methods for organic solvents.
The coating material of the invention comprises at least two, in particular
two, compounds
of the general formula I:
X-O-Y(-OH)-Z-Gr (I).
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In this formula the variables have the following definitions:
X is aromatic radical having 6 to 14, preferably 6 to 10, carbon atoms,
heterocyclic
aromatic radical having 5 to 20, preferably 6 to 10, ring atoms or alkyl
radical
having 6 to 30, preferably 8 to 20, particularly 10 to 16, carbon atoms;
preferably
aromatic radical having 6 to 10 carbon atoms or alkyl radical having 10 to 16
carbon atoms; particularly phenyl radical or lauryl radical;
Y is trivalent organic radical, preferably aliphatic radical, preferably
aliphatic radical
having 3 carbon atoms, particularly 1,2,3-propanetriyl;
Z is linking functional group, preferably selected from the group consisting
of ether,
thioether, carboxylic ester, thiocarboxylic ester, carbonate, thiocarbonate,
phosphoric ester, thiophosphoric ester, phosphonic ester, thiophosphonic
ester,
phosphite, thiophosphite, sulfonic ester, amide, amine, thioamide,
phosphoramide,
thiophosphoramide, phosphonamide, thiophosphonamide, sulfonamide, imide,
urethane, hydrazide, urea, thiourea, carbonyl, thiocarbonyl, sulfone,
sulfoxide or
siloxane groups. Preferred among these groups are the ether, carboxylic ester,
carbonate, carboxamide, urea, urethane, imide and carbonate groups, preferably
carboxylic ester group, and particularly carboxylic ester group linked to the
radicals
Y and Gr in accordance with the general formula II:
>Y-O-(O=)C-Gr (II),
and
Gr is organic radical having at least one, especially one, group which can be
activated
with actinic radiation;
with the proviso that at least one, especially one, of the at ieast two,
especially two,
compounds (A) contains an aromatic or heterocyclic aromatic, especially
aromatic, radical
X (= compound Al) and at least one, especially one, of the at least two,
especially two,
compounds (A) contains an alkyl radical X (= compound A2).
Actinic radiation means electromagnetic radiation, such as near infrared
(NIR), visible
light, UV radiation, X-rays or gamma radiation, preferably UV radiation, and
corpuscular
radiation, such as electron beams, alpha radiation, beta radiation, proton
beams or
neutron beams, preferably electron beams. In particular the actinic radiation
constitutes
electron beams.
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The groups which can be activated with actinic radiation contain at least one,
especially
one, bond which can be activated with actinic radiation. By this is meant a
bond which,
when subjected to actinic radiation, becomes reactive and, together with other
activated
bonds of its kind, enters into polymerization reactions and/or crosslinking
reactions which
proceed in accordance with free-radical and/or ionic mechanisms. Examples of
suitable
bonds are carbon-hydrogen single bonds or carbon-carbon, carbon-oxygen, carbon-
nitrogen, carbon-phosphorus or carbon-silicon single bonds or double bonds, or
carbon-
carbon triple bonds. Of these, the carbon-carbon double bonds and triple bonds
are
advantageous and are therefore used with preference in accordance with the
invention.
The carbon-carbon double bonds are particularly advantageous, and so are used
with
particular preference. For the sake of brevity they are referred to below as
"double bonds".
The double bonds are preferably present in organic radicals Gr of the general
formula III:
R2 R'
C=C (III).
R3 R-
In the general formula III the variables have the following definitions:
R is single bond to an atom of the above-described linking functional group Z,
particularly carbon-carbon single bond to the carbon atom of a carbonyloxy
group and divalent organic radical, preferably carbon-carbon single bond;
and
R1, R 2
and R" are hydrogen atom and organic raUicai;
it being possible for at least two of the radicals R, R1, R2 and R3 to be
cyclically linked to
one another.
Examples of suitable divalent organic radicals R comprise or consist of
alkylene,
cycloalkylene and/or aryiene groups. Highly suitable alkylene groups contain
one carbon
atom or 2 to 6 carbon atoms. Highly suitable cycloalkylene groups contain 4 to
10,
particularly 6, carbon atoms. Highly suitable arylene groups contain 6 to 10,
particularly 6,
carbon atoms.
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Examples of suitable organic radicals R', R2, and R3 comprise or consist of
alkyl,
cycloalkyl and/or aryl groups. Highly suitable alkyl groups contain one carbon
atom or 2 to
6 carbon atoms. Highly suitable cycloalkyl groups contain 4 to 10,
particularly 6, carbon
atoms. Highly suitable aryl groups contain 6 to 10, particularly 6, carbon
atoms.
The organic radicals R, R1, R2, and R3 may be substituted or unsubstituted.
The
substituents, however, must not disrupt the implementation of the process of
the invention
and/or inhibit the activation of the groups with actinic radiation. Preferably
the organic
radicals R, R1, R2, and R3 are unsubstituted.
Examples of particularly suitable radicals Gr of the general formula III are
vinyl, 1-
methylvinyl, 1-ethylvinyl, propen-1-yl, styryl, cyclohexenyl,
endomethylenecyclohexyl,
norbornenyl, and dicyclopentadieny! groups, especially vinyl groups.
Accordingly the particularly preferred radicals of the general formula (IV)
-Z-Gr (IV)
are (meth)acrylate, ethacrylate, crotonate, cinnamate, cyclohexenecarboxylate,
endomethylenecyclohexanecarboxylate, norbornenecarboxylate, and dicyclo-
pentadienecarboxylate groups, preferably (meth)acrylate groups, especially
acrylate
groups.
Examples of particularly advantageous compounds (Al) are phenyl glycidyl ether
monoacrylates, as sold, for example, by Cray Valley under the name Aromatic
Epoxy
Acrylate CN 131 B.
Examples of particularly advantageous compounds (A2) are lauryl glycidyl ether
monoacrylates, such as are sold, for example, by Cray Valley under the name
Aliphatic
Epoxy Acrylate Monofunctional CN152.
~he amount of the compounds (A) in the coating material of the invention may
vary widely
and is guided by the requirements of the case in hand. Preferably the amount
of the
compounds (Al), based in each case on the coating material of the invention,
is 10% to
60%, preferably 15% to 50%, and in particular 20% to 40% by weight. The amount
of the
compounds (A2), based in each case on the coating material of the invention,
is
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preferably 5% to 50%, more preferably 10% to 40%, and in particular 15% to 30%
by
weight. The weight ratio of (Al) to (A2) is preferably 4:1 to 0.8:1, more
preferably 3:1 to
1.2:1, very preferably 2:1 to 1.2:1, and in particular 1.6:1 to 1.4:1.
The coating material of the invention comprises at least one, especially one,
acidic
corrosion-inhibiting pigment (B) based on polyphosphoric acid. Preference is
given to
using aluminum polyphosphates and zinc polyphosphates, especially aluminum
polyphosphates. Aluminum polyphosphates are conventional products and are
sold, for
example, under the brand name Targon by BK Giulini.
The amount of the pigment (B) in the coating material of the invention may
vary very
widely and is guided by the requirements of the case in hand. The amount of
pigment (B),
based in each case on the coating material of the invention, is preferably 1%
to 60%,
more preferably 4% to 50%, and in particular 5% to 40% by weight.
The coating material of the invention further comprises at least one
constituent (C)
selected from the group consisting of nanoparticles and electrically
conductive pigments.
As nanoparticles (C) use is made of at least one, especially one, kind of
nanoparticles. It
is preferred to use inorganic nanoparticles (C).
The nanoparticles (C) are preferably selected from the group consisting of
main-group
metals and transition-group metals and their compounds. The main-group and
transition-
group metals are preferably selected from metals of main groups three to five,
transition
groups three to six, and transition groups one and two of the Periodic Table
of the
Elements, and also the lanthanides. Particular preference is given to using
boron,
aluminum, gallium, silicon, germanium, tin, arsenic, antimony, silver, zinc,
titanium,
zirconium, hafnium, vanadium, niobium, tantalum, moiybdenum, tungsten, and
cerium,
especially aluminum, silicon, silver, cerium, titanium, and zirconium.
The compounds of the metals are preferably the oxides, oxide hydrates,
sulfates or
phosphates.
Preference is given to silver, silicon dioxide, aluminum oxide, aluminum oxide
hydrate,
titanium dioxide, zirconium oxide, cerium oxide, and mixtures thereof;
particular
preference to silver, cerium oxide, silicon dioxide, aluminum oxide hydrate,
and mixtures
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thereof; very particular preference to silicon dioxide; and a special
preference to pyrogenic
silicon dioxide (fumed silica).
The nanoparticles (C) have a primary particle size of preferably < 50 nm, more
preferably
5 to 50 nm, in particular 10 to 30 nm.
The electrically conductive pigment (C) is preferably selected from the group
consisting of
metal-doped oxides of zinc, tin, indium, and antimony, preferably from indium-
tin oxide,
aluminum-zinc oxide, titanium-tin oxide, Antimon-Antimonoxid and antimony-tin
oxide. The
electrically conductive pigment (C) may also be a nanoscale pigment.
The amount of the constituents (C) in the coating material of the invention is
preferably
1% to 60%, more preferably 4% to 50%, and in particular 5% to 40% by weight,
based in
each case on the coating material of the invention.
The coating material of the invention may further comprise at least one
additive (D) in
effective amounts. The additive (D) is preferably selected from the group
consisting of
water, polyphosphoric acid, phosphonic acids having at least one group which
can be
activated with actinic radiation, acidic esters of polyphosphoric acid and of
at least one
compound containing at least one hydroxyl group and at least one group which
can be
activated with actinic radiation, acidic esters of monophosphoric acid and of
at least one
compound containing at least one hydroxyl group and at least one group which
can be
activated with actinic radiation, compounds having at least one group which
can be
activated with actinic radiation, other than the compounds (A), driers, non-
(C), organic and
inorganic, colored and achromatic, optical effect, electrically conductive,
magnetically
shielding, and fluorescent pigments, transparent and opaque, organic and
inorganic fillers,
nanoparticles, oligomeric and polymeric binders, UV absorbers, light
stabilizers, free-
radical scavengers, photoinitiators, devoiatiiizers, slip additives, poiyi i
ier izatiivi i inhibitCr s,
defoamers, emulsifiers and wetting agents, adhesion promoters, leveling
agents, film-
forming assistants, rheology control additives, and flame retardants.
Preferably the additive (D) is selected from the group consisting of water;
polyphosphoric
acid; phosphonic acids having at least one group which can be activated with
actinic
radiation, especially vinylphosphonic acid; and also acidic esters of
polyphosphoric acid
and of at least one compound containing at least one hydroxyl group and at
least one
group which can be activated with actinic radiation, and acidic esters of
monophosphoric
acid and at least one compound containing at least one hydroxyl group and at
least one
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group which can be activated with actinic radiation, such as are described,
for example, in
German patent application DE 102 56 265 Al, page 7, paragraphs [0057] to
[0062], in
conjunction with page 6, paragraphs [0044] and [0045]. Water is preferably
used in an
amount of 1% to 10%, more preferably 2% to 8%, and in particular 3% to 7% by
weight,
based in each case on the coating material of the invention. The phosphonic
acids and
the acidic esters of monophosphoric acid and polyphosphoric acid are used
preferably in
an amount of 0.05% to 5%, preferably 0.5% to 4%, and in particular 1% to 3% by
weight,
based in each case on the coating material of the invention.
The coating material of the invention is prepared preferably by mixing the
above-
described constituents in suitable mixing apparatus such as stirred tanks,
agitator mills,
extruders, compounders, Ultraturrax devices, inline dissolvers, static mixers,
micromixers,
toothed-wheel dispersers, pressure release nozzles and/or microfluidizers. It
is preferred
here to work in the absence of light with a wavelength k < 550 nm or in the
complete
absence of light, in order to prevent premature crosslinking of the
constituents containing
groups which can be activated with actinic radiation.
The coating materials of the invention are outstandingly suitable for
producing coatings of
all kinds. They are particularly suitable for use as coi.l coating materials.
Additionally they
are outstandingly suitable for producing coatings on all utility metals,
particularly on bright
steel, galvanized, electrolytically zincked, and phosphated steel, zinc, and
aluminum, on
coatings, especially primer coatings, and on SMC (Sheet Moulded Compounds) and
BMC
(Bulk Moulded Compounds). In this context, the coatings of the invention are
outstandingly suitable for use as clearcoats, topcoats, temporary or permanent
protective
coats, primer coatings, seals, and antifingerprint coatings, but especially as
primer
coatings.
Surprisingly the coatings of the invention, particularly the primer coatings
of the invention,
even on unpretreated metal surfaces, such as on unpretreated HDG (hot dip
galvanized)
steel, meet at least the requirements of class IV of the Usinor specification
for
components for outdoor use, particularly in respect of adhesion, flexibility,
hardness,
chemical resistance, intercoat adhesion, and corrosion control effect, in
full.
In terms of method the application of the coating material of the invention
exhibits no
particularities, but can instead take place by any customary application
methods, such as
spraying, knifecoating, brushing, flow coating, dipping, trickling or rolling,
for example.
Generally speaking, it is advisable to operate in the absence of actinic
radiation, in order
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to prevent premature crosslinking of the coating materials of the invention.
Following
application, the water present in the coating material of the invention can be
simply
evaporated, also referred to as flash-off. This is preferably done by brief
inductive heating
of the metal substrates.
Particularly suitable for curing the applied coating materials of the
invention with actinic
radiation are electron beam sources, as described, for example, A. Goldschmidt
and
H.-J. Streitberger, BASF-Handbuch Lackiertechnik, Vincentz Verlag, Hannover,
2002,
pages 638 to 641, or in Rompp Lexikon Lacke und Druckfarben, Georg Thieme
Verlag,
Stuttgart New York, 1998, "electron-beam emitters", "electron-beam curing",
and "electron
beams".
For irradiation it is preferred to use a radiation dose of 10 to 200,
preferably 20 to 100, and
in particular 30 to 80 kGy (kilograys).
The radiation intensity may vary widely. It is guided in particular by the
radiation dose on
the one hand and the irradiation time on the other. The irradiation time is
guided, for a
given radiation dose, by the belt speed or advance rate of the substrates in
the irradiation
unit, and vice versa.
It is a particular advantage of the coating material of the invention that it
can also be only
part-cured and in said part-cured state can be overcoated with at least one
further coating
material, in particular with a coating material curable with actinic
radiation, after which all
of the applied films are cured jointly with actinic radiation. This further
shortens the
operating times, and further enhances the intercoat adhesion. Overall, by
virtue of the use
of the coating material of the invention, it is no longer necessary to heat
the metal sheets
to PMTs of 240 C or more in the coil coating process. Also superfluous are the
suction
withdrawal and disposal of voiatiie organic compoun~s, thlereby dlifowing sigi
iificai ~t
reductions in the cost and complexity associated with apparatus, safety
equipment, and
energy.
The resultant coatings of the invention are highly flexible, can be deformed
very greatly
without damage, are resistant to chemicals, weathering, condensation, and salt
water, and
adhere very well to the substrates and to other coatings. In combination with
all of these
qualities, they also impart an outstanding visual impression. They can be
overcoated
without problems, after which the resulting composites or laminates have an
outstanding
intercoat adhesion.
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Examples
Example 1
The preparation of coating material I
To prepare coating material I first a mixture of 33.25 parts by weight of
phenyl glycidyl
ether monoacrylate (CN 131B from Cray Valley), 22.8 parts by weight of lauryl
glycidyl
ether monoacrylate (CN 152 from Cray Valley), 1.12 parts by weight of
polypropylene
glycol monoacrylate (PAM 300 from Rhodia), 1.12 parts by weight of an epoxy
resin
(Epikote 862), 5.82 parts by weight of water, 2.91 parts by weight of a
polyphosphoric
ester of 4-hydroxybutyl acrylate (prepared by reacting 80 parts by weight of 4-
hydroxybutyl acrylate and 20 parts by weight of polyphosphoric acid having a
diphosphorus pentoxide content of 84% by weight; 4-hydroxybutyl acrylate
excess: 20%
by weight), 1.68 parts by weight of low-viscosity poiyvinylbutyral (Pioloform
BN 18 from
Wacker), 18.5 parts by weight of aluminum polyphosphate pigment (Targon WA
2886
from BK Giulini), 6 parts by weight of nanoparticles based on silica (Nyasil
6200 from
Nyacol Nano Technologies), and 9 parts by weight of titanium dioxide pigment
(Tioxide
TR 81) was prepared. The mixture was homogenized in an Ultraturrax at a
rotational
speed of 1800/min for 20 minutes.
Coating material 1 was fully stable on storage in the absence of actinic
radiation for at
least one month. It was outstandingly suitable for producing primer coatings.
Example 2
The preparation of coating material 2
To prepare coating material 2 first a mixture of 28.7 parts by weight of
phenyl glycidyl
ether monoacrylate (CN 131B from Cray Valley), 19.14 parts by weight of lauryl
glycidyl
ether monoacrylate (CN 152 from Cray Valley), 0.957 parts by weight of
polypropylene
glycol monoacrylate (PAM 300 from Rhodia), 0.957 parts by weight of an epoxy
resin
(EpikoteO 862), 4.78 parts by weight of water, 2.39 parts by weight of a
polyphosphoric
ester of 4-hydroxybutyl acrylate (prepared by reacting 80 parts by weight of 4-
hydroxybutyl acrylate and 20 parts by weight of polyphosphoric acid having a
diphosphorus pentoxide content of 84% by weight; 4-hydroxybutyl acrylate
excess: 20%
by weight), 9.57 parts by weight of aluminum polyphosphate pigment (Targon WA
2886
= CA 02606874 2007-11-02
BASF Coatings AG 15
PAT 01304 PCT
April 27, 2006
from BK Giulini), and 33.5 parts by weight of an electrically conductive
pigment based on
a metal-doped oxide was prepared. The mixture was homogenized in an
Ultraturrax at a
rotational speed of 1800/min for 20 minutes.
Coating material 2 was fully stable on storage in the absence of actinic
radiation for at
least one month. It was outstandingly suitable for producing primer coatings.
Examples 3 and 4
The production of primer coatings using coating materials 1 and 2 from
Examples I
and 2
The substrates used were unpretreated, HDG (hot dipped galvanized) steel
panels from
Chemetall.
In the case of Example 3, coating material 1 was applied in a film thickness
of 6 to 7 pm.
The water present therein was evaporated at 125 C for one minute. The
resulting film was
cured with electron beams (50 kGy).
The resulting coating was outstandingly deformable and had an outstanding
corrosion
control effect (T-Bend test: 0, and tape: 0; salt water spray test: 7 days,
satisfactory (sat.)).
It could be overcoated with conventional topcoats. The resulting laminates
exhibited
outstanding intercoat adhesion and an outstanding corrosion control effect
(salt water
spray test: 21 days, sat.).
In the case of Example 4, coating material 2 was applied in a film thickness
of 2 to 3 pm.
The water present therein was evaporated at 120 C for 30 seconds. The
resulting film
was cured with electron beams (50 kGy).
The resulting coating could be overcoated readily with electrocoat materials.
In the course
of the thermal curing thereof there is no blistering or other surface defects.
The intercoat
adhesion, deformability, and corrosion control effect were outstanding (T-Bend
test: 0, and
tape: 0.5; salt water spray test: 120 hours, sat.).
